1. Field of the Invention
The present invention relates to thermoplastic film, and more particularly perforated film having a prepunched tube hole suitable for use in applications such as textile yarn dyeing.
2. Description of the Related Art
In the dyeing of textile yarns, such as cotton, acrylic, wool and blends of various natural and synthetic yarns, a slotted cylindrical plastic or stainless steel tube, known as a dye tube, is typically used to hold a quantity of yarn wound around the tube. This arrangement is known as a yarn package or dye package. These dye packages are processed in a dyeing vat known as a dye kier. A dye of a suitable color typically heated up to about 150.degree. C. and at a pressure of up to about 80 psi, is forced through the yarn in the dyeing process.
This process, because of the high temperature and pressures involved, and the overall environment of the process, can result in some damage to the yarn material, particularly at the outer face of the yarn package.
An effective solution to this problem has been the use of perforated films, of a type such as the PY film sold by the Cryovac Division of W. R. Grace & Co.--Conn., to overwrap the yarn package. If the film is also a shrink film, then a tight fitting but porous overwrap is provided which helps to protect the yarn during the dyeing process, while allowing the dye to flow through the yarn to the outer circumference of the package, and vice versa.
One limitation of conventional perforated film wrapping of the dye package is that the ends of the dye package are not provided with an even tight overwrap up to the tube. This can result in unacceptable dyeing results, especially with rigid, noncompressable, short, low profile dye packages.